Re: Bimini top
You sure can, you may end up with some unwanted holes where the old brackets were but aside from that no problem, you could even leave the old brackets on and just put the new where they need to go.
Graigs list is the only place I can thinnk for a used one, that is one of those things that people normally don't sell so you might have a problem even finding one in decent shape.
Google a boat salvage yard and see if there is one in your area, that would be a good source also.